1. Field of Invention
The present invention is generally related to any printing apparatus or system that can produce an output test pattern or image and monitor the output images to determine errors or faults.
2. Description of Related Art
In a continuous feed printing system, e.g., based on solid inkjet technology, multiple print heads are distributed over a long print zone to obtain desired color and image resolutions in an output document. Each print head may have one or more jets for outputting colorant such as ink onto a web 10. For example, as shown in FIG. 1, a continuous paper web 10 may be moved in a process direction P during printing. The web 10 may have an imageable area 14 (or print area) and images 12 of a document for output may be printed on the web 10 within the area 14. Because faulty jets can produce undesirable output images and/or delay processing time of a job, printing systems typically include detection devices for detecting faulty jets. For example, a sensor 20 may be provided adjacent the web 10 to read test patterns 16 that are printed by the jets within an inter-document zone (IDZ) region 18 between document images 12, as illustrated in FIG. 1. As known in the art, these test patterns 16 may be scanned or sensed in a cross process direction C using one or more sensors 20, such as a full width array (FWA) sensor or an image sensor. Based on the sensed test patterns the system can determine or detect faulty or missing jets.
In current systems, when missing jet detection is turned on, test patterns 16 are printed in the IDZ region 18 and the sensor(s) 20 scan test patterns 16 and provide feedback to the system if it is determined that any jets are not firing (or some other similar fault related to the jets). Typically, if a jet is deemed faulty, the system is designed to substitute neighboring jets to fire and replace the missing jet, and notifies the customer which jet(s) is(are) not firing. However, some customers will turn this detection feature off. For example, when a customer is not able to cut out or chip out test patterns using their existing finishing equipment capabilities (e.g., when the web 10 is cut for output), the customer may opt to stop the system from printing test patterns and thus sensing the same. However, if a system cannot print and read the test patterns, correction for faulty or missing jets will not be performed during print jobs, and, therefore, output image quality will be degraded (e.g., because the system will not know when jets do not fire or are intermittent). Generally, such problems may exist on any printing system that can produce a test pattern, scan or sense the test pattern, and compensate for image quality defects, because such detection may be turned off.
A method and system that offers a customer flexibility to adjust conditions related to printing and sensing (scanning) test patterns (e.g., when and where test patterns are printed and/or sensed) would improve customer satisfaction without hindering the image quality of printed documents.